Predictive Role Of 12-h Arterial Lactate In Acute Kidney Injury Associated With Off-pump Coronary Artery Bypass Grafting

Objectives:This observational study aims to explore the predictive role of postoperative arterial lactate in off-pump coronary artery bypass grafting(CABG)-associated acute kidney injury(AKI)and determine the diagnostic threshold.We expected to construct a clinically available prediction model.Materials and Methods:We retrospectively reviewed patients(n=500)undergoing off-pump CABG from August 2020 to August 2021 at the Department of Cardiovascular Surgery,Qilu Hospital of Shandong University.Patients were divided into AKI and non-AKI groups according to the criteria of Kidney Disease:Improving Global Outcomes guideline.Logistic regression analysis was used to confirm the independent risk factors and construct a nomogram prediction model of off-pump CABG-associated AKI.Receiver operating characteristic curve was performed to evaluate the discrimination ability,and HosmerLemeshow(HL)goodness of fit test was performed to evaluate the calibration ability.We repeated 1000 times using bootstrap method for internal validation and plotted the calibration curve.Clinical decision curve was performed to evaluate the clinical utility of the prediction model.Results:A total of 103 patients developed AKI,and the incidence of off-pump CABG-associated AKI was 20.6%.Female gender,preoperative albumin,baseline serum creatinine,12-h postoperative arterial lactate and duration of mechanical ventilation were independent risk factors.The area under the receiver operating characteristic curve(AUC)of 12-h postoperative arterial lactate for predicting off-pump CABG-associated AKI was 0.756 and the diagnostic threshold was 1.85mmol/L.The sensitivity was 71.8%and the specificity was 67.8%.The prediction model that incorporated all independent risk factors showed reliable predictive ability(AUC=0.846)and calibration ability(the P value of HL test equals 0.642).The calibrated c-index after internal validation was 0.839.The calibration curve confirmed the great agreement between predicted probabilities and actual probabilities.The clinical decision curve indicated the good clinical utility.Total hospital stay,intensive care unit stay,occurrence of other postoperative complications,and 28-day mortality were all significantly higher in AKI group compared to non-AKI group.Conclusion:12-h postoperative arterial lactate was a validated predictive biomarker for off-pump CABG-associated AKI,and the diagnostic threshold was 1.85mmol/L.We constructed a nomogram prediction model that facilitates the early recognition and management of off-pump CABG-associated AKI based on analysis of independent risk factors.